The previous owner of my SPF was enough of a motor head (and happened to own just about every peice of CNC type equipment going) so he designed and built his own EFI system. Turned out great and works great. Just make sure that if you aren't getting a Mass Flo system, get a good computer for the EFI. I have a MegaSquirt ECU controlling my stuff and I wouldn't suggest it to anybody who isn't into serious learning curves. It does the job, but I wish I had a simpler system on mine....
James